Include debug logging in Robot log.html

[JFoederer]

While using robotkernel I was missing the debug logging from my underlying libraries. With this PR debug logging is included in the log.html files, but hidden by default. It can be revealed by selecting debug from the pull-down menu in the upper-right corner.

[github-actions]

👈 Try it on ReadTheDocs

[datakurre]

@JFoederer Thanks for contributing this. I was made aware that this is missing, but have been thinking something way too complex to configure it "Jupyter way". It's probably good to include debug log by default now and if there is ever need to suppress log, do it then.

This will increase saved notebook sizes (logs are included when executed notebooks are saved and shared), but probably it is not a real problem.

[JFoederer]

Thank you for accepting the PR @datakurre. You are right about the increase in size, but that shouldn't be an issue. If people are really bothered by that, they can change the loglevel in the logging module. Then it is already filtered out before it gets to the Robot logs. If no debug lines are present in the log, the pulldown menu is not shown, so you are back in the old situation.